IS 10434 (Part 1) :2003 *m Tiwl-w,WFTmf * hwT* IJIdww (- mTliMmw%it@'n ( H7TJpl%wr) Indian Standard INSTALLATION, MAINTENANCE AND OBSERVATION OF DEFORMATION MEASURING DEVICES IN CONCRETE AND MASONRY DAMS . .. -- GUIDELINES *,.* PART 1 RESISTANCE . *62 ..s ( TYPE JOINTMETERS First Revisio; ) ICS 93.160 0 BIS 2003 BUREAU MANAK q OF IN DIAN STANDARDS MARC BHAVAN, 9 BAHADUR SHAH ZAFAR NEW DELHI 110002 April 2003 Price Group 6 Hydraulic Structures Instrumentation Sectional Committee, WRD 16 FOREWORD This Indian Standard (Part 1) (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by the Hydraulic Structures Instrumentation Sectional Committee had been approved by the Water Resources Division Council. To minimize cracking, large straight gravity and arch other by transverse and longitudinal contraction joints. behaviour, contraction joints are grouted with cement opened to maximum. Measurement of joints movement should be pumped into the joints. gravity dams are made in blocks, separated from each To restore the dam to its monolithic state for integrated grout. Grouting of joints is done when the joints have during grouting operation will indicate how much grout Measurements of joint movements subsequent to the completion of the grouting of contraction joints, provides information regarding the behaviour of the grouted joints. Surface measurements and joint movements will be useful for watching shearing movement of joints. These measurements can be done with mechanical strain gauges applied to gauge inserts. However, full reliance cannot be placed on the surface measurements as all parts of joints do not open at the same time and not even the same amount. Internal joint movement may, therefore, also need to be measured. Vibrating wires type jointmeters for measurement of joint movement at the surface and in the interior of concrete and masonry dams are being separately covered. This standard has been published in two parts. Part 2 of the standard covers foundation deformation devices. measuring This standard was first published in 1982. This first revision is being taken up to incorporate the knowledge gained during the use of the standard. In this revision reference clause has been added and some addition has been made in the method of installation of resistance type jointmeter. The composition of the Committee responsible for the formulation of this standard is given at Annex E. IS 10434 (Part 1): 2003 Indian Standard INSTALLATION, MAINTENANCE AND OBSERVATION OF DEFORMATION MEASURING DEVICES IN CONCRETE AND MASONRY DAMS -- GUIDELINES PART 1 RESISTANCE TYPE JOINTMETERS ( 1 SCOPE This standard (Part 1) covers the details of installation, maintenance and observation of resistance type jointmeters of tie embedded type for measurement of joint movements at the surface and in the interior of concrete and masonry dams. 2 REFERENCES The following standards contain provisions, which through reference in this text constitute provisions of this standard. At the time of publication the editions indicated were valid. All standards are subject to revision and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below: Title IS No. 6524:1972 Code of practice for installation and observation of instruments for temperature measurement inside dams; resistance type thermometers Code of practice for selection, splicing, installation and providing protection to the open ends of cables used for connecting resistance type measuring devices in concrete and masonry dams First Revision) One 450 conical contact point is attached to each member. For taking measurements the conical points are inserted into the inserts fixed in the drilled holes defining a predetermined gauge length. The essential features of the instrument are shown in Fig. 1A. NOTE -- The gauge is available in two gauge lengths (254 mm and 508 mm) and appropriate gauge suitable for the given situation should be used. 3.1.2 Inserts Inserts may be made of mild steel or stainless steel, but stainless steel inserts are recommended though they may be expensive. The mild steel inserts also last well without rusting, if due care is taken, such as cleaning and greasing. Inserts of nylon or any other suitable material may also be used. The insert shall have conical depressions at the centre for providing line of contact with the conical points and a typical insert is shown in Fig. lB. 3.1.2.1 The inserts are placed in such a position as to indicate opening and closing movements of the joint and any sliding movement of the adjacent block. NOTE -- Adequate protective covers over each installation of inserts may be provided to guard against damage due to misuse. 10334:1982 3.2 Number, Location and Layout The inserts should be installed on the surface at points corresponding to the locations of jointmeters inside the dam. These should also be fixed inside galleries across joints, where these are accessible and at points corresponding to the jointmeter locations. 3.2.1 Where surface cracks are present and are considered capable of influencing the structural integrity of the dam, inserts shall also be placed across such cracks for observation of crack behaviour under imposed loadings. 3.2.2 The arrangement for fixing the inserts across the joint is shown in Fig. 1 C and 1 D. The arrangement shown in Fig. 1 C is preferable as it gives the width of opening simply by the difference in readings. 1 3 MEASUREMENTS OF JOINT MOVEMENTS OF SURFACE BY DETACHABLE GAUGES 3.1 Prhciple and Construction Measurements of joint movements at surface or at the locations accessible from galleries are made by detachable gauges. 3.1.1 Whittemore Type Gauge The gauge is a self-contained instrument consisting essentially of two frame members bounded together by two elastic hinges for parallel frictionless motion. IS 10434 (Part 1) :2003 3.3 Method of Installation After the concrete is well set, holes should be drilled carefully at specified locations. The holes shall be cleaned of all loose material. The insert shall then be placed in the holes and aligned so as to be normal to the surface of concrete in which it is being fixed. The space around the insert shall be backfilled with expansive mortar. Suitable gauges shall be used in aligning the axes of inserts and in getting the gauge length accurately. 3.4 Observations The inserts shall be well cleaned for taking the readings so that the instrument pins are placed in exactly the same position. The detachable gauge shall be placed into the inserts and the readings on the dial gauge shall be observed. In order to correct the detachable gauges for the effect of temperature varia~ions, readings of the gauge shall be taken on a standard unstressed invar bar placed in the immediate vicinity of observation station. 3.4.1 A proforma for the record of observations given in Annex A. 3.5 Analysis of Data Analysis of observed data in case of the instrument not compensated for temperature correction is made as under: If readings at time tl are p, and i, for the concrete and invar and for time t2 are p2 and iz, the variation in the joint opening is given by: is In the case of arrangement of inserts shown in Fig. 1 D, measurements are made to determine the distances Al, B, and C,. `x=P-p') -(i2-i') 1A Schematic View of Whittemore Type Gauge u 17 1B Whittemore and Marion Gauge Inserts 1C Position of the Gauge Inserts 1D Position of the Gauge Inserts Relative to the Joints Relative to the Joints AHdimensions in millimetres. FIG. 1 INSTRUMENTS FOR MEASUREMENTS OF JOINT MOVEMENTSAT SURFACE 2 IS 10434 (Part 1) :2003 The horizontal distance xl at time [1 is obtained from the equation: x,. and vertical distance `y, = where, at time tl A I = measured distance between parallel to joint plane, inserts on line A;B;+C; 2A, 4.101.1 Construction and principle B 1= distance between upper two inserts across the joint, and Cl = distance between lower-two inserts across the joint. Similarly X2and y? at time tz are calculated. Between times [.l and [~, the horizontal movement of the joint is M ­ xl and slide movement is y2 ­ yl. 3.6 Source of Error Seating the gauge is one of the chief sources of error. Application of excessive longitudinal force should be avoided for seating the points in the inserts. Other sources of error are the dial indicator and temperature changes. 4 MEASUREMENT OF INTERNAL MOVEMENTS BY JOINTMETERS %1 Jointmeters Two kinds of jointmeters for internal joint movement measurements are in use: a) Unbended resistance type, and b) Vibrating wire type. 4.1.1 Unbended (Curl.son Type) Resistance Type Joint meter JOINT The meter is in the form of a long brass cylinder with a flange at one end and a threaded hub on the other to fit a tapped socket. In practice, the socket is embedded in the concrete of a leading monolith to form the anchorage for the meter on one side of the contraction joint to be measured. The flange on the meter is engaged and held by the embedding concrete in the following monolith on the opposite side of the joint. Inside the brass case, a steel framework supports ceramic pulleys and a long single loop of steel wire, which is held in tension by small coil springs. A greater part of the displacement which the meter undergoes in use is taken up by the springs (see Fig. 2). The brass tube is completely filled with a corrosion resistant oil. A separate sealing chamber is provided for terminating the three rubber covered conductor cables that connect the jointmeter to the terminal boxes in the galleries. The instrument is designed to take advantage of two electrical properties of steel wire, namely, resistance varies directly with temperature and resistance varies directly with tension. When the ends of the jointmeter are pulled apart by opening of a joint, the outer or expansion loop elongates and increases in tension and consequently in resistance as well. At the same time, the inner or contraction loop decreases in resistance as it shortens. The ratio of the resistance of the expansion loop divided by the resistance of the contraction loop is used as a measure of joint opening. Temperature is measured by taking the sum of the resistances of expansion and contraction coils. Since there may be considerable shearing or movement in contraction joints as adjacent blocks cool at different rates, the jointmeter is designed to withstand a shearing movement of 2.5 mm by reducing the frame section at the ends to serve as elastic hinges. A flexible bellows forms the central section of the --. ~-:--v"----"-`I , +..--....--flTAPE SLEEvING IN pLAcE 200­ ­ 260-255 ----------------Y II I `"a \,,,,,,,,,,, BRAIDED 57 FABRIC FLAT SLEEVING `., STEEL SpRING - MUSIC IPIANO) WIRE COIL ` k rl~li snn AI-c ------FR {N . . PI . ---END ANCHOR ~\~REo 3-CONOUCT OR RUlBBER l-n -.) VERED CABLE END ANCHOR TOP VIEW (INTER-COIL All NOT SHOWN) dimensionsin millimetres. FIG. 2 ELASTICWIRE STRAINMETER(CARLSONTYPE) 3 `L `WHITE BLACK IS 10434 (Part 1) :2003 jointmeter to take the longitudinal and shear motions of the case without undue straining. Measurements of resistance ratio and resistance are made by connecting the three conductor cables to the binding posts of a standard wheatstone bridge, circuit test set in specified order in accordance with the manufacturer's instructions. 4.2 Number and Location 4.2.1 Number of jointmeters required to be provided in any given dam will depend upon the dimensions, block layout, provision of transverse and longitudinal joints or transverse joints only, configuration of the foundation profile, presence of specially treated foundation features under the dam, and the extent to which measurements of joint behaviour would prove adequate in representing the joint movements for the entire structure. 4.2.2 In the case of dams built in V-shaped canyon, jointmeters should be installed in at least three blocks, namely, one central block representing deepest and maximum section of the dam, and a block each in the abutment portions representing blocks built on steeply sloping abutments. In other cases they maybe installed one in the overflow section and one in the non-overflow section or any other representative block as may be decided. At a given elevation, the jointmeters in each of these blocks should be installed at the centre of the transverse dimensions of the monoliths in the blocks, and should be spaced about 15 m vertically in the height of the longitudinal and transverse contraction joints as the grouting lifts (zoning of joints by provision of metal seal) are limited to about 15 m in height. This spacing may be modified in the top portion of the joint if joint height does not permit of 15 m spacing for the entire height. 4.3 Method of Installation 4.3.1 Unbended Resistance Ty@eJoin[meter f) b) c) not more than 15 cm below the top of the lift for easy installation. Screw the socket cm the plug. When socket installation is complete, care should be taken by the workmen not to hang things on the socket or use it as a step in getting out of the form or misuse it in any other way as to cause misalignment. As a precaution it is good practice to run a few stay wires to the form to keep the socket in position and prevent its misalignment. The arrangement is shown in Fig. 3. If it is considered that for the particular concrete being used, the force exerted by the nails in the plug and ties is greater than the bond resistance on the socket, to prevent pulling it out during form removal. The anchor should necessarily be provided in the case of masonry dams. If the cable leads are to run in the block in which the socket is embedded, recess should be provided adjacent to the socket into which not less than 1 m of the cable should be coiled. d) e) 4.3.1.3 After the low block reaches the elevation in which the jointmeter itself is to be embedded, the following procedure shall be followed: a) After the form is removed, remove the plug, fill greased cloth and screw in the hexagonal headed plug; Complete the lift at the jointmeter location; Dig back at the location until the plug is uncovered leaving a small trench about 30 cm x 30 cm; Back out the plug and greased cloth and insert the jointmeter, screwing it uprigh~ While fixing the moveable end of jointmeter, allowance may be given for the meter, to respond for expansion and contraction that is in both the directions. Tie the jointmeter cable lead out of the pour (if cable is embedded in the high block) and backfill with 75 mm maximum concrete, hand puddling the concrete around the meten and Next day, splice the meter cable; and the cable extension may preferably be done at the time of embedment to allow observation to be made. b) c) d) e) 4.3.1.1 Prior to the embedment of the jointmeters, each instrument should be thoroughly checked for the meter resistance as also for the lead resistance and these should be entered in the proforma given in Annex B. The resistance ratios before splicing and after splicing should also be recorded in the above proforma. 4.3.1.2 Jointmeters are supplied equipped with a socket which should be first embedded in the high block. The socket is further provided with a slotted plug in which two holes are drilled. Procedure for the installation of jointmeter at a contraction joint consists of the following steps: a) Nail the plug, slotted side out, to the wooden form at the jointmeter location. This should be g) 4.4 Cables and Conduits Guidelines IS 10334. regarding this aspect are provided in 4.4.1 Additional length of cable should be attached to the jointmeter by means of splicing, done either with the help of electric heat vulcanizer or by applying self bonding tape. 4 IS 10434 (Part 1) :2003 W.-?". -.:: K* WfOODEN RECESS Box x...~:~ ",.. .b" ..,... i-" `~" `.: & ,.. . Jl\l,-.:i."..: b'..,..*.1 . *..".m(----Step 1 =CABLE WRAPPED IN BURLAP ANO FRICTION TAPE FOR 45 cm AND COILED INSIOE RECESS 1 BOX. END SEALED. installation in High Block n f CABLE TIED UP OUT OF CONCRETE LIFT HEXAGOtd HEAD PLUG CABLE SPLICED AFTER COMPLETION OF LIFT J!!lw HHI HOLE DUO AFTER COMPLETION OF LIFT JOINTMETER SCREWED INTO SOCKET,AND BACKFILL PLACED BY HANO ROUND JOlN7METER BEFORE INITIAL SET. [it . f h. 1 a Step 2 Preparation in Low Block Step 3 Jointmeter installation FIG.3 JOINTMETERINSTALLATION 4.4.2 Provision of 10 percent or 1.5 m whichever is more, over the estimated length of cable should be allowed for possible variation from selected route. 4.4.3 Each meter should be identified by a letter prefix. The normal prefix used forjointmeter is JM-1, JM-2, etc. After splicing, a copper band with the instrument identification number stamped or punched on it is crimped to the cable about 1 m from the free end. In addition a few more marks consisting of the identification number marked on white tape should be placed around the cable near the reading end. 4.4.4 Provision contained in 4.3 of IS 6524 shall also apply to the jointmeter installations. 4.5 Terminal Boards Cables shall be terminated in suitable terminal boards. Jointmeter numbers shall be indicated in the terminal boards also as described in 4.4.3. If the terminal boards 5 IS 10434 (Part 1) :2003 are to be placed in the inspection gallery, they shall be mounted in a nitch, preferably on the downstream side. The terminal boards shall be moisture proof. 4.6 Observations 4.6.1 Observations of the resistance ratio and resistance of the jointmeter should be made by connecting the meter conductors (until these are soldered to the terminal contacts on terminal boards in galleries) to the binding posts of the standard wheatstone bridge in the order specified by the manufacturer. Subsequent to their terminations on the terminal boards in galleries, observations ofjointmeter should be made by connecting the jointmeter terminations to the test set binding posts through the test lead equipped with a female plug in socket at one end and the individual conductors equipped with metallic terminations for connections to the test set binding post at the other end. Care should be taken to connect the cable leads in the order specified by the manufacturer to ensure correct and reliable measurements. 4.6.2 The adopted: a) b) c) d) e) f) @ following reading schedule shall be 4.7 Sources of Error 4.7.1 Unbended Resistance The error may be due to: a) b) c) d) e) 4.7.2 Presence of moisture on the terminal panels, Loose circuit connections of the test set, Faulty cable leads, Presence of deposit on terminal contacts, and Low voltage of test set batteries. Vibrating Wire Type Jointmeter Type Jointmeter Accuracy of the reading is not impaired due to resistance of cables. However, the test set has electronic circuits and the components are affected by temperature and shock. 4.8 Collection of Complimentary Data The following properties of the concrete or mortar in which jointmeters are embedded shall be defined: a) b) Coefficient of thermal expansion, Autogenous growth. and 4.9 Analysis of Data 4.9.1 Unbended Resistance Type Jointmeter Immediately after embedment, Every 3 h for the next 30 h, Every 12 h for the next four days, Once a day till the concrete temperature rises to a maximum (usually about two weeks), Twice weekly for the next one month, Weekly for next two months or until the completion of contraction joint grouting, and Fortnightly afterwards. Analysis of the data should be done by transcribing the observed data to the `Join tmeter Data Sheet' shown in Annex D and following the procedure given in 4.9.2. 4.9.2 The calibration data of the meter as supplied by the manufacturer shall be filled in the space provided in the top portion of the form, against particular items. The value of the corrected calibration constant maybe calculated by using the following equation: ~ _ y. C.$.89) 4.6.3 Forms of Record Observations shall be recorded directly on the printed field reading form shown in Annex C. These forms should be got printed sufficiently in advance and kept ready. Duplicate copy of observations should be prepared simultaneously. The original should be sent to design office, or to the office entrusted with the analysis of the data and the duplicate retained in the field record office for future reference. where c= c= y= R= calibration constant (corrected), original calibration constant, resistance of a pair of conductor cables, and meter resistance at O°C. 6 -- Date N I Time Reservoir water level Tail water level Initial, pi Subsequent, 4 u I Observed distance between inserts fixed at right angle joint pl -1 (P2 - P]) m Intial, il Subsequent, (i, - i,) iz Observed length of invar base w I . Movement of joint (+Ve indicates opening of joint) (P2-PI) -- -(iz - il) N Remarks -- IS 10434 (Part 1) :2003 ANNEX B (Clause 4.3. 1.1) PROFORMA UNBONDED FOR RECORD OF OBSERVATIONS RESISTANCE TYPE JOINT METERS TESTS PRE-EMBEDMENT Project: .......................................................................... Instrument No.: ............................................................. Air temperature: .............................................................. No.: ....................................................... Manufacturers Project No.: ................................................................... Location: ....................................................................... Wet bulb temperature: 1 Resistance Before Cables Splicing: i) White-black iii) Green-black ii) White-green iv) Resistance one pair .................................................... 2 Resistance Ratio (instrument only): i) Direct ratio (white-green-black) ii) Reverse ratio (black-green-white) 3 Individual Conductor Resistance: i) Length iii) Green ii) Black iv) White 4 Resistance of Instrument after Cable Splicing: i) White-black iii) Green-black ii) White-green iv) Resistance one pair 5 Resistance Ratio (instrument with cable): i) Direct ratio (white-green-black) ii) Reverse ratio (black-green-white) Date of test: Date of embedment: Name and signature of observer NOTES: 8 IS 10434 (Part 1): 2003 ANNEX C (Clause 4.6.3) PROFORMA PROJECT ....................................................................................... FOR RECORD OF OBSERVATIONS UNBONDED RESISTANCE JOINTMETERS FIELD READINGS AFTER EMBEDMENT Date Time Resistance Ratio TYPE Instrument No. Previous Readings Date Resistance Ratio Observer's Signature JM 1 2 3 4 5 6 7 , 9 IS 10434 (Part 1) :2003 ANNEX D (Clause 4.9. 1) PROFORMA FOR RECORD OF OBSERVATIONS DATA SHEET FOR UNBONDED RESISTANCE TYPE JOINTMETER Sheet No. : .......................................................... Project: ................................................................ No. : .................................................. data I Jointmeter Calibration I Location : ............................................................ Block : Chainage and Location: ............................................................. Meter resistance at (A)OC1)......................................[B1)] ohm Change in temperature per ohm change in resistance .................................................[c1)]0c I 1 Calibration Ratio in closed position ............................................% Original calibration constant .................................... [D1)] mm per 0,01% ratio change constant corrected for leads ..................(D) mm per O.01% ratio change Resistance of leads at ...............................................0C...............................ohm (pair) Date Time TOMI Resistance ohms Lead ResisUdnce ohms Meter Resistance ohms Temperature "C Resistance Ratio % Change in Ratio % (8) (1) (2) (3) (4) (5) (6) (7) 4= mm Indicated Movement (9) Remarks (10) Explanations for columnsincludinganalysis: Col 3: Col 4: Total resistance of meter as measured in the field. With a 4-conductor cable the cell resistance is measured directly, and WIS column may be left blank. Resistance of the white and black conductors, as measured directly during the splicing operations. Asan attemative, a reasonably accurate value may be determined by subtracting the total resistance of the contraction and expansion coils measured in series from the sum of the resistances of the contraction and expansion coils measured separately. Resistance of meter excluding cable leads. It is obtained by subtracting CO14 from co] 3 with 4-conductor resistance is measured directly. Temperature of the meter, obtained by subtracting (B) from the cell resistanceinCO15, adding the product to (A). The resistance mtio of the meter as measured with the test set. Total change in resistance ratio(CO17) from a selected initial vatue when the joint is known to be closed. at about 24 h after the concrete/masonry has been placed. Proper algebraic sign should be shown. cable the meter Col 5: ~01 6: multiplying the difference by (C) and Col 7: Co] 8: c'ol9: This is usuatly taken over into CO19, Multiply values in COI8 by the correlated calibration constant (D), The algebraic signs of co] 8 we carried positi;; values indicating an opening of the joint with respect to the initial position and vice-versa. NOTE -- Since the magnitude of the thermal length changes of the meter and concrete/masonry due to changes in temperature are significantly small relative to the joint movements being measured and the range of the meter, no temperature correction is made. Temperature data is of general interest and provides a means for detecting faulty operation of the measuring point. 1) CalibraliontiaV~ furnished by the manufacturer. 10 IS 10434 (Part 1): 2003 ANNEX E (Foreword) COMMITTEE COMPOSITION Sectional Committee, WRD 16 Hydraulic Structures Instrumentation Organization National Hydro ElectricPowerCorporationLtd, Faridabad Representative(s) SHRIBRUENDRA SHARMA(Chairrnun) SHRt S. P. GUFTA AIMILLtd, New Deihi Bhakra Beas Management Board, Nangal Township, Punjab Central Board of Irrigation & Power,NewDelhi CentralBuildingResearchinstitute,Roorkee CentralWater& Power Research Station, Purre Central Water Commission, New Delhi SHRt S. C. JAIN (Alternate) DIRECTOR/DAM SAFETY EXECUTtVE ENGINEER (Alternate) SHRIS. P. KAUSHISH SHRIT. S. MURTHY(Alternate) SHR1J. N. VAMH SHRIY. PANDEY(Alternate) sHRtMATl v. M, BENDRE SHSU C. K. HAYATNAGARXAR (Alternate) DUWZTORINSTRUMENTATION DIREOOR ERDD (N&W)(Alternate) Consulting Engineering Services (1) Ltd, New Delhi Damodar Valley Corporation Ltd, Dhanbad lmcaldio-l